Tube bending apparatus



Sept. 9, 1969 Filed O. N. GARDNER TUBE BENDING APPARATUS March 2 Sheets-Sheet 1 Il l\ 7 Mrk@ ATTORNEYS Sept. 9, 1969 o. N. GARDNER 3,465,550

TUBE BENDING APPARATUS Filed March 6, 1968 2 Sheets-$heet '/NVENTOR 0l? VILLE N. GARDNER ATTORNEYS United States Pattent O 3,465,560 TUBE BENDING APPARATUS Orville N. Gardner, 1406 Stewart Ave., Levittown, Pa. 19057 Filed Mar. 6, 1968, Ser. No. 710,899 Int. Cl. B21c 51/00; B21d 11/04, 9/05 U.S. Cl. 72-32 12 Claims ABSTRACT OF THE DISCLOSURE Tube bending apparatus wherein a bender and a tube supporting means are disposed on a frame, and manually operable mechanical actuator means are provided for advancing the tube supporting means and tube therein incrementally with respect to the frame, thereby permitting application of a bending force to the tube by the bender at predetermined intervals along the tube. In one form of the invention, the actuator is a lever having an adjustable throw, and a ratchet wheel coupled to the lever, the tube supporting means being coupled to the ratchet wheel by a sprocket and endless chain.

This invention relates to tube bending apparatus, and more particularly, to apparatus wherein a tube to be bent is fed through a bender, and incremental bends placed at predetermined spaced locations therealong, the sum of such incremental bends being a bendv of desired total angle and radius.

Conventionally, tubular members such as pipe, conduit or the like (to be denoted hereinafter generically as tubes) are bent about a curved form having a tube contacting channel. It has been necessary to provide forms having channels corresponding to the diameter of each different size tube to be bent.

It has been proposed to eliminate the need for the curved form by applying to the tube incremental bends at closely spaced points, the sum of the individual bends approximating a single bend of desired radius. As a practical matter, if a suiiicient number of bends is used, and such bends are spaced closely enough, the result is a smooth and continuous bend, virtually indistinguishable from other continuous bends. One form of an apparatus intended to bend tubes in the foregoing manner is shown in U.S. Patent 3,075,568. In this apparatus, the location and spacing of bend points is mechanically determined once the location of the initial bend is established. A 90 degree bend is made in five, ten or twenty shots, those numbers being determined by the characteristics of the control system. Some bends, particularly those of large radius, require more than twenty individual bends. Additional bends are applied by re-positioning the workpiece after twenty shots, and then applying the further bends. Re-positioning of the workpiece partway through the bending operation greatly increases the chance of displacement of the bending plane midway through the bend. The result of such displacement is a twisted bend section, a so-called dog-leg. Tubes so bent are useless, and must be discarded.

With the present apparatus, any number of shots up to practical limits is obtainable for a given bend. The workpiece, once mounted in the apparatus, need not be displaced during operation. The likelihood of producing ice dog-legs is virtually eliminated. The apparatus, in a preferred form, employs a simple hand-operated lever to advance the workpiece between shots. The amount which the workpiece advances with each throw of the lever is determined by an adjustable stop, and movement of the lever to the extent permitted by the adjustable stop ensures advancement of. the workpiece by the precise amount desired. Visual determination of bend points is eliminated, as are complex and frequently troublesome electromechanical control systems.

Thus, it is an object of the present invention to provide a novel tube bending apparatus.

It is another object to provide an apparatus capable of applying bends of preselected radius to tubular workpieces.

A further object is to provide a simple mechanical means for advancing tubular workpieces a predetermined amount with respect to a bender.

A still further object of the invention is to provide in a tube bending apparatus a clear visual indication of the amount of bend in a workpiece at any intermediate stage of a bending operation.

It is another object to provide a bending apparatus wherein a minimum amount of operator skill is required for successful operation.

It is a still further object to provide a bending apparatus wherein a bender and a workpiece support are mounted on a frame, the support being movable with respect to the frame toward the workpiece, and wherein manually operable ratchet means are provided to move the support with respect to the frame by a predetermined amount.

Other objects will appear hereinafter.

The foregoing and other objects are realized by a tube bending apparatus wherein a bender and a pipe supporting means are disposed on a frame, and manually operable mechanical means are provided for advancing the tube supporting means and tube therein incrementally with respect to the frame. In a preferred form of the invention, the manually operated means comprises a lever having an adjustable throw, a ratchet wheel coupled to the lever, and means responsive to movement of the ratchet wheel for moving the pipe supporting means with respect to the frame.

For the purpose of illustrating the invention, there is shown in the drawings a form which is presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown.

FIGURE l is a side elevation view showing apparatus in accordance with the present invention.

FIGURE 2 is a top plan view of the apparatus seen in FIGURE 1.

FIGURE 3 is an end elevation view, viewing the apparatus as indicated by the line 3-3 in FIGURE 1.

FIGURE 4 is a cross-sectional view taken along the line 4-4 in FIGURE l.

FIGURE 5 is a mechanical detail of a portion of the apparatus.

FIGURE 6 is a perspective view showing a visual indicator forming a part of the apparatus.

Referring now to the drawings in detail, wherein like numerals indicate like elements, there is seen a tube bending apparatus designated generally by the reference numeral 10. The tube bending apparatus includes a frame 12. A bender, designated generally by the reference numeral 14, is pivoted to the frame 12. Upstanding brackets 16 and a horizontally disposed pivot pin 18 may be provided for this purpose. A tube supporting means, designated generally by the reference numeral 20, slidably supported by the frame 12. Slidable support for the tube supporting means 20 is provided by horizontally spaced, upwardly facing channel members 22 disposed on opposite sides of the frame 12. The tube supporting means 20 is provided with depending channel-engaging members 24, best seen in FIGURE 4, slidably received in the respective channel members.

Also mounted on the frame 12 is an actuator means, designated generally by the reference numeral 26, for the tube supporting means 20. Motion transmitting means 28, illustrated as an endless chain, transmits motion from the actuator means 26 to the tube supporting means 20.

Referring again to FIGURE l, the actuator means 26 is seen in detail. The actuator means 26 comprises a lever 30 pivoted to the frame 12. A bracket 32 secured to the underside of the frame 12 provides a convenient location for a pivot axis 34 of the lever 30. At its upper end, the lever 30 includes a handle portion 36, readily grasped by the operator. Pivotably coupled to a medial portion of the lever 30 is a link 38. A pawl 40, to be described in detail later, is secured to an end of the link 38.

A ratchet wheel 42 is xed to a transverse shaft 44, pivoted in the frame 12. The shaft 44 is best seen in FIGURE 2. Also fixed to the shaft 44 is a handwheel. The handwheel 46 is disposed exteriorly of the frame 12, in a position for easy manipulation by an operator. A sprocket wheel 48 is fixed to a central portion of the transverse shaft 44. The chain constituting the motion transmitting means 28 is received over the sprocket wheel 48.

Rotation of the lever 30 about the pivot axis 34 is limited. Thus, a fixed limit stop 50 may be provided. As shown, the xed limit stop 50 limits movement of the lever 30 in a counterclockwise direction in FIGURE 1. An adjustable limit stop 52 is provided to limit movement of the lever 30 in a clockwise direction.

Referring now to FIGURE 5, the link 38 is seen to comprise a pair of spaced, similar link members 38a and 38b, each having an end pivoted to the lever 30 by a common pivot pin 54. The link members 38a and 38b include enlarged end portions 56. The enlarged end portions 56 have corresponding horizontally aligned openings 58 therein. The pawl 40, preferably a hardened steel cylindrical member is received in the aligned openings 58. A generally U-shaped bail straddles enlarged end portions S6 and retains pawl 40 in aligned openings 58. The manner in which pawl 40 engages the ratchet wheel 42 is apparent in FIGURE 5. The ratchet wheel 42 includes teeth 62 having surfaces 64 adapted to be engaged and driven by the pawl 40 upon counterclockwise movement of the lever 30. Teeth 62 also include surfaces 66 disposed so that pawl 40 rides freely thereover when the lever 30 is moved in a clockwise direction. Pawl 40 and ratchet 42 dene a one-way drive mechanism, ratchet wheel 42 being rotated in a counterclockwise direction in response to counterclockwise rotation of lever 30 about its pivot axis 34. For a purpose to be explained later, adjustment of adjustable limit stop 52 determines the throw of lever 30, and accordingly, the degree of rotation of ratchet wheel 42 for a given stroke of lever 30 from adjustable limit stop 52 to fixed limit stop 50.

Rotation of ratchet wheel 42 in the aforesaid manner causes a like rotation of transverse shaft 44 and sprocket wheel 48. Rotation of sprocket wheel 48 is applied to the chain 28. A second transverse shaft 68 is pivoted to frame 12 at a position spaced from transverse shaft 44. As is best seen in FIGURE 4, a sprocket wheel 70 is provided on transverse shaft 68. Sprocket wheel 70 is aligned with sprocket wheel 48, and receives endless chain 28. Sprocket wheel 70 serves as an idler for endless chain 28. A depending member 72 coupled to tube supporting means 20 is secured to endless chain 28. It should now be apparent that rotation of lever 30 to cause counterclockwise rotation of ratchet wheel 42 results in linear motion of tube supporting means 20 with respect to frame 12 to left in FIGURE l. It should also be apparent that adjustment of adjustable limit stop 52 to provide a particular throw of lever 30 results in movement of tube supporting means 20 a predetermined distance with respect to frame 12. A tube 74, fixed to tube supporting means 20 is of course moved a similar distance.

The bender 14 is of conventional construction, not perse novel. The bender 14 includes a frame 76 comprising spaced generally triangular plates. The frame 76 of bender 14 is pivotably coupled to frame 12 by the previously described pivot pin 18. Also pivoted about pivot pin 18 is a roller 78. A shoe 80, pivoted to frame 76 of bender 14 at a corner remote from pivot pin 18, provides several selectable faces 82. Such faces are contoured for engagement with the outer surfaces of tubes of different diameter. A hydraulic cylinder 84 is fixed to frame 76, and has its piston coupled to a tube-engaging shoe 88. Actuation of hydraulic cylinder 84 causes tube-engaging shoe 88 to apply a force to the workpiece, tube 74. Application of such a force results in application by shoe of a bending moment tending to bend the lefthand end of tube 74 (FIGURE l) upwardly. The point about which the bending occurs is beneath tube-engaging shoe 88.

Referring now to FIGURE 6, there is seen a visual indicator designated generally by the reference numeral 90, whereby the precise angle of bend in a given workpiece, up to 90 degrees, can he readily determined. The indicator 90 includes a frame 92. The frame 92 has a protractor portion 94. The protractor 94 includes a scale having graduations of 1 of arc, with larger graduations every 5. In a presently preferred form, plates 96 are applied on opposite sides of frame 92. A pendulum type pointer 98, pivoted to a pivot pin moves within an opening in frame 92. Means 102 is provided for securing indicator 90 directly to a workpiece. For use with tubes of ferrous metals, means 102 may take the form of a magnet. An alternative form of means 102 is a clamp of universal size, adapted to embrace the tube.

In FIGURE 1, indicator 90 is seen in position on tube 74.

Operation of the apparatus 10 to bend tube 74 will now be described in detail. As is apparent from the foregoing description, a given rotation of ratchet wheel 42 results in movement of tube supporting means 20 by a corresponding amount. By suitable adjustment of adjustable limit stop 52, pawl 40 can be made to traverse n teeth 62 of ratchet wheel 42 as an operator moves lever 30 in a clockwise direction. The manner in which adjustable limit stop S2 determines the extent of movement of tube supporting means 20 with respect to the frame 12 is now apparent. Depending on the diameter of ratchet wheel 42 and the number of teeth 62 thereof, each tooth represents a given linear movement of tube supporting means 20. In one operative embodiment, ratchet wheel 42 had 144 teeth, and each tooth represented 1/16 inch movement of tube supporting means 20.

Initially, it is necessary to determine and mark the initial bend point on a workpiece. By rule of thumb, for most tube sizes, the length of a bend along the tube center line is approximated as 1.55 times the radius of the bend. The distance between shots is the length of the bend divided by the number of shots. Such distance is the linear distance which tube supporting 20 is advanced between shots. Knowing the advance of tube supporting means 20 for each tooth 62 on ratchet wheel 42, it is a simple matter to compute the number of teeth to be traversed by pawl 40 in each stroke, and to set adjustable llmit stop 52 accordingly. As a practical matter, once the number of shots selected, the number of teeth per stroke can be tabulated for bends of various radii. Such a table is reproduced below:

Teeth on ratchet wheel per throw Radius of bend (inches): (l revolution: 144 teeth) 1 8 1Indicates a `90 bend is completed by a whole number of revolutions of ratchet wheel 42.

Other tablesmay be provided for commonly used numbers of shots, for example, 18 shots at 5/shot; 20 shots at 4.5/shot; 25 shots at 3.6"/shot; 45 shots at 2/shot; and 30 shots at 3 shot.

Assuming a 90 total bend is to be applied, the angle produced by each shot is 90 divided by the number of bends. After adjustment of adjustable limit stop 52, the initial shot may be applied by actuating hydraulic cylinder 84 in the conventional manner. Indicator 90 shows the progress of the bending operation. Referring to FIG- URE l, as the lefthand end of tube 74 bends upwardly, pendulum pointer 98 begins to traverse protractor portion 94, and indicates dellection of tube 74 from the horizontal. In practice, bending force is applied by hydraulic cylinder 84 until tube 74 is bent slightly beyond the ntended initial angular deection, thereby allowing for spring back after the force is relieved. The tube 74 is next advanced by movement of level 30 and another shot performed. The foregoing steps are repeated sequentially until the entire bend is complete.

With bends of this sort, the ratchet wheel itself gives a convenient indication of the progress of the bend. By placing a mark on ratchet wheel 42 and observing the position of the mark, an operator has a ready indication of completion of the desired number of shots. Handwheel 46 provides a means for manual operation of ratchet wheel 42 when necessary. Handwheel 46 is used, for example, to position the initial bend point on the tube 74, designated in FIGURE 1 by letter I, beneath tube engaging shoe 88.

For repeat Work, wherein similar bends are to be applied to similar tubes, a handy gauge, designated generally by the reference numeral 104 and best seen in FIGURES 1, 2 and 3, is used. Gauge 104 comprises a calibrated rod 106. Rod 106 may be secured to frame 76 of bender 14. An adjustable member 108, which comprises a pair of spaced, interconnected collars is disposed on rod 106. A stop member 110 is rotatably received on rod 106 between the collars of adjustable member 108. In its operative position, stop member 110 extends downwardly to a lower limit position wherein it abuts a portion of adjustable member 108, and is adapted to contact a leading edge of tube 74. yIn an inoperative position, best seen in FIGURE 3, stop member 110 is rotated upwardly to abut and be supported by another portion of adjustable member 108. In operation, stop member 110 provides a guide for instantaneous positioning of a tube 74 for an initial bend. Where a series of like pieces are to be made, the above-described initial marking need be performed only on the iirst such piece. Prior to bending of the piece, ad-

justable member 108 is moved along rod 106 to a position wherein stop member 110 abuts a leading edge of the piece. Adjustable member 108 can then be secured, by a set screw or the like, to rod 106. Subsequent pieces can be positioned against stop member 110 and bending performed as usual. Stop member 110 is rotated to its inoperative position during the bending operation itself.

Another aspect of the invention is the means, seen in FIGURES 1 and 3, whereby creepage of the tube 74 during initial bending is eliminated. There is a tendency for a tube 74 to shift to the right in FIGURE 1 due to the horizontal component of the bending force applied by the shoe 80. Such tendency is most pronounced with large diameter tubes (over 21/2 inches outside diameter), and during initial application of bending force. In FIGURES 1 and 3, there is seen a means designated generally by the reference numeral 112 for applying a force to the tube 74 independently of the force applied by the bender 14 for obviating the problem of creepage. The means 112 comprises a vertical guide member 114 fixed to the frame 12. A force applying member 116 having a generally T- shaped head is vertically slidable in the guide member 114. The force applying member 116 is secured at its lower end to a rod 118. Adjustable means 120 may be provided to adjust the length of the combined rod 118 and force applying member 116 for a purpose to be eX- plained. A lower end of rod 118 is pivoted to a link 122. A medial portion of the link 122 is pivoted, at 124, to a base plate 126. A foot-engaging treadle 128 is disposed at one end of link 122.

When an operator applies a foot to treadle 128, link 122 may be rotated about pivot 124. Such pivoting causes rod 118 to move upwardly, carrying with it force applying member 116. Force applying member 116, as is best seen in FIGURE 3, is coupled to bender 14. In FIGURE 3, force applying member 116 rests against shoe 80. By applying force to shoe 80 by means of force applying member 116, rm engagement of shoe 80 with a tube 74 is maintained. Such engagement has been found to greatly reduce creepage, thereby ensuring accurately placed bends on the tube 74. Means 112 also serves to level bender 14 prior to bending and when no tube 74 is in apparatus 10. Adjustable means 120 provides convenient adjustment of the combined length of force applying member 116 and rod 118 to initially level bender 14.

The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, reference should be made to the appended claims, rather than to the foregoing speciication as indicating the scope of the invention.

I claim:

1. Tube bending apparatus comprising a frame, bending means on said frame, tube supporting means on said frame spaced from said bending means, means on said frame for moving said tube supporting means relative to said frame to advance the tube with respect to said bending means, said means for moving said tube supporting means comprising a manual actuator coupled to said frame, means coupled to said actuator and said tube supporting means for transmitting motion from said actuator to said tube supporting means, and adjustable means coupled to said actuator for limiting movement of said actuator, whereby movement of said actuator moves said tube supporting means a predetermined incremental distance relative to said frame.

2. Tube bending apparatus in accordance with claim 1 wherein said actuator comprises a ratchet wheel pivotrably coupled to said frame, an actuator lever coupled to said frame, and a drive pawl coupled to said actuator and adapted to drivingly engage said ratchet Wheel.

3. Tube bending apparatus in accordance with claim 2, said adjustable means for limiting movement of said actuator comprising a selectively movable mechanical stop for blocking movement of said actuator lever.

4. Tube bending apparatus in accordance with claim 1 wherein said means for transmitting motion from said actuator to said tube supporting means comprises a sprocket rotatable in response to movement of said actuator, and endless chain means coupled to said sprocket and said tube supporting means.

5. Tube bending apparatus in accordance with claim 1 wherein said bending means is pivotably supported by said frame for pivoting about a horizontal axis, a hydraulic cylinder spaced from said axis, a rst shoe member associated with said hydraulic cylinder and adapted to engage a tube, a second shoe member on said bending means spaced from said axis further than said hydraulic cylinder for applying a bending force to the tube, and means coupled to said frame for applying a force to the tube independently of said hydraulic cylinder through said second shoe member, whereby creepage of the tube in the bending means is substantially eliminated.

6. Tube bending apparatus in accordance with claim 5 wherein said means for applying a force to the tube independently of said hydraulic cylinder comprises a vertically movable force applying member for contacting said bending means, guide means on said frame for directing movement of said force applying member, and foot actuated means for moving and applying force to said force applying member.

7. Tube bending apparatus in accordance with claim 1, and a visual indicator adapted to be secured to a tube in said apparatus, said indicator comprising a protractor elcment movable with the tube, and a gravity actuator pointer associated with said protractor element for indicating the degree of bend in the tube.

8. Tube bending apparatus in accordance with claim 7, and magnetic means on said indicator for coupling said indicator to the tube.

9. Tube bending apparatus in accordance with claim 1, and a stop member coupled to said frame for engaging a leading edge of a tube in said apparatus to determine an initial bend point on the tube.

10. Tube bending apparatus in accordance with claim 9, and a rod member coupled to said apparatus and extending in a direction longitudinally of said frame, said 8 stop member being pivotably coupled to said rod member and rotatably mounted thereon for rotation between operative and inoperative positions.

11. Tube bending apparatus comprising a frame, bending means on said frame, tube supporting means on said frame spaced from said bending means, means on said frame for moving said tube supporting means relative to said frame to advance a tube incrementally with respect to said bending means, means coupling said bending means to said frame for pivoting about a horizontal axis, a hydraulic cylinder on said bending means spaced from said axis, a first shoe member associated with said hydraulic cylinder and adapted to engage a tube, a second shoe member on said bending means spaced from said axis further than said hydraulic cylinder for applying a bending force to the tube, and means coupled to said frame for applying a force to the tube independently of said hydraulic cylinder through said second shoe member, whereby creepage of the tube in the bending means is substantially eliminated.

12. Tube bending apparatus in accordance with claim 11 wherein said means for applying a force to the tube independently of said hydraulic cylinder comprises a vertically movable force-applying member for contacting said bending means, guide means on said frame for directing movement of said force-applying member, and foot-actuated means for moving and applying force to said forceapplying member.

References Cited UNITED STATES PATENTS RONALD 'D. GREFE, Primary Examiner U.S. Cl. X.R. 72-320, 388 

